Project Description Cancer initiation and progression depend on profound alterations of cell metabolism to meet the demand for energy and biosynthesis. Elucidation of molecular mechanisms underlying this ?metabolic reprogramming?, which includes increased glucose and glutamine uptake, aerobic glycolysis and altered lipid metabolism, will provide opportunities for devising novel strategies for prevention and therapy for cancers including lung cancer, a deadly disease that is a heavy public health burden. The hexosamine biosynthesis pathway (HBP) produces uridine dinucleotide phosphate-N-acetyl-glucosamine (UDP-GlcNAc) for protein glycosylation, thus couples nutrient sensing and protein quality control to metabolism and gene expression to support cell proliferation and survival. The role of HBP in lung carcinogenesis is currently unknown. Our preliminary studies suggested that L-glutamine:D-fructose-6-phosphate amidotransferase (GFAT), the rate-limiting enzyme of HBP which determines GlcNAc flux, overexpressed in lung cancer and facilitated lung cancer development and progression. The goal of this proposal is to elucidate the role of GFAT and HBP in human bronchial epithelial cell (HBEC) transformation, an early stage of lung carcinogenesis, through evaluating the communication between HBP and endoplasmic reticulum unfolded protein response, and the link of HBP to fatty acid metabolism. Two aims are designed to achieve our goal: Aim 1: To determine the mechanisms underlying GFAT induction by cigarette smoke carcinogens and the cytoprotective role of GFAT in HBECs; Aim 2: To investigate the mechanisms through which GFAT promotes HBEC transformation. We expect the data obtained from this proposal will establish a foundation for future applications further delineating the role of GFAT and HBP in lung carcinogenesis, and validate the feasibility and efficacy of targeting this pathway for lung cancer intervention.